An inner rotor-type permanent magnet embedded synchronous motor (an Interior Permanent Magnet (IPM) motor) is provided with a rotating shaft, a rotor held by the rotating shaft, a stator arranged on the outer circumference of the rotor, and a yoke supporting the rotating shaft and the stator. The rotor of the IPM motor is provided with a cylindrical core made of non-oriented electromagnetic steel plates, permanent magnets attached to the core, and end plates that prevent the permanent magnets from coming loose from the core. The permanent magnets of the IPM motor are arranged inside slit-shaped through-holes formed in the core.
Conventionally, for the purpose of simplifying an assembly of the permanent magnets to the core and for preventing thermal stress from occurring due to a change in temperature, each of the permanent magnets arranged inside the through-holes is designed to be smaller than the size of each of the through-holes formed in the core.
With respect to the rotor for the motor to which the permanent magnets are fixed, technologies disclosed in Patent Documents 1 and 2 are known, for example.